What are extended release products
Release medication in controlled manner to reduce drug blood level fluctuation and dosing frequency
What are delayed release products
Enteric coated, designed to pass through stomach unaltered and release medication in intestinal tract
What are sustained release products
Provide immediate release of drug to promptly provide therapeutic effect and then gradual release of additional drug to maintain this effect
Advantages of sustained release products
Reduced no. doses per day increases compliance, less fluctuation in plasma drug concentration
Properties of drugs suitable for extended release
Neither slow nor very fast absorption and excretion, uniformly absorbed from GIT, admin in relatively small dose, possess good margin of safety, treat chronic rather than acute conditions
Main mechanisms to control release
Control dissolution or diffusion of drug
What are ion exchange resins
Cross linked polymers that have ionised groups capable of exchanging ions, used to make chemical complexes with the drug
What sort of resin is in cation exchange
Acidic group
What sort of resin is in anion exchange
Amine or quaternary amine
How does a hydrophilic matrix work
Drug dispersed in soluble/hydrophilic matrix, matrix swells when outermost polymers in contact with water, hydrate to form viscous gel, any further fluid has to diffuse through this gel layer to slowly hydrate tablet
Advantages of hydrophilic matrix systems
Simple, cheap and safe excipients, capable of sustaining high drug loads, erodible, easy to manufacture, possible to obtain zero order release
Role of gel/matrix modifiers in hydrophilic matrix systems
Modify diffusional characteristics of gel layer, enhance drug diffusion and release, can allow more complete uniform hydration of gel matrix
Role of solubilisers and pH modifiers in hydrophilic matrix systems
Help with dissolution of drug
Why are lubricants needed in hydrophilic matrix systems
Reduce die wall friction, prevent sticking to punches
How do insoluble lipid matrix systems work
Drug contained in hydrophobic matrix which remains intact during drug release
Ingredients of insoluble lipid matrix systems
Wax matrix former, channelling agent, solubiliser/pH modifier, antiadherent/glidant, lubricant
How do insoluble polymer matrix systems work
Drug embedded in polymer matrix that doesn’t dissolve, drug release like leaching out of a sponge, matrix remains intact in GIT
How do membrane controlled delivery systems work
Rate controlling via outer membrane through which drug must diffuse, water diffuses in to dissolve drug, drug solution diffuses out
Single unit systems
Coated tablet
Multiple unit systems
Coated spheroids filled into capsule shells or compressed into tablet
How do osmotically controlled systems work
Core contains drug +/- osmotic agent, surrounded by semipermeable polymer membrane, orifice for drug delivery , osmotic agent draws water in, form saturated solution inside, increased pressure causes saturated solution to flow out
What does zero order drug release in osmotic devices depend on
Cs, osmotic pressure, size of delivery orifice, type of membrane
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GIT Introduction17
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GIT Infections93
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IBS65
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IBD38
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Nutrition and dietary supplements66
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Oral and dental health33
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Hepatic disease55
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GORD38
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Peptic ulcer disease29
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Antiemetics45
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Sources of variability18
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Hepatic extraction ratio17
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Bioequivalance12
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Powders and granules32
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Particle size reduction + particle size distribution19
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Properties of powders33
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Mixing26
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Tablets81
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Oral solid dosage forms19
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Coating of tablets and multiparticulates33
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Solid oral MR dosage forms22
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Capsules23
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Rectal and vaginal solid dosage forms25
